U.S. patent application number 11/226100 was filed with the patent office on 2006-12-28 for composition and method for reducing chemical oxygen demand in water.
Invention is credited to Roy W. Martin.
Application Number | 20060293178 11/226100 |
Document ID | / |
Family ID | 46322653 |
Filed Date | 2006-12-28 |
United States Patent
Application |
20060293178 |
Kind Code |
A1 |
Martin; Roy W. |
December 28, 2006 |
Composition and method for reducing chemical oxygen demand in
water
Abstract
A method and composition for reducing chemical oxygen demand is
presented. The composition includes a persulfate donor, a
transition metal catalyst in contact with the persulfate donor, and
a cationic electrolyte. When the composition is contacted by water,
the transition metal catalyst reacts with persulfate and reduces
the persulfate concentration in the water. The composition allows
the use of persulfate, which is known to cause irritation to users
of aquatic facilities (e.g., pools, spas) that come in contact with
it. As the persulfate concentration is reduced rapidly in the water
by the catalyzed reaction, the persulfate-containing product may be
applied while the aquatic facilities are being used. A free halogen
donor may be incorporated into the composition. The composition may
be in the form of powder, granules (coated or uncoated), or
agglomerate. The cationic electrolyte facilitates the removal of
the catalyst from the water.
Inventors: |
Martin; Roy W.; (Downers
Grove, IL) |
Correspondence
Address: |
DLA PIPER RUDNICK GRAY CARY US, LLP
2000 UNIVERSITY AVENUE
E. PALO ALTO
CA
94303-2248
US
|
Family ID: |
46322653 |
Appl. No.: |
11/226100 |
Filed: |
September 14, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11158676 |
Jun 22, 2005 |
|
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11226100 |
Sep 14, 2005 |
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Current U.S.
Class: |
502/321 ;
210/631 |
Current CPC
Class: |
B01J 23/75 20130101;
B01J 35/0006 20130101; B01J 23/72 20130101; C02F 1/725 20130101;
C02F 2103/42 20130101; B01J 23/50 20130101; C02F 1/76 20130101;
B01J 23/42 20130101; C02F 1/722 20130101; B01J 23/745 20130101;
B01J 23/28 20130101 |
Class at
Publication: |
502/321 ;
210/631 |
International
Class: |
B01J 23/00 20060101
B01J023/00; C02F 9/00 20060101 C02F009/00 |
Claims
1. A composition for reducing chemical oxygen demand in water, the
composition comprising: a persulfate donor; a transition metal
catalyst in contact with the persulfate donor; and a cationic
electrolyte.
2. The composition of claim 1, wherein the transition metal
catalyst makes up between about 0.01 wt. % and about 10 wt. % of
the composition, the cationic electrolyte makes up from 0.01 wt %
to about 20 wt. % of the composition, and the persulfate donor
makes up from about 70 wt. % to about 99.98 wt. % of the
composition.
3. The composition of claim 1, wherein the transition metal
catalyst makes up between about 0.01 wt. % and about 10 wt. % of
the composition.
4. The composition of claim 1, wherein the cationic electrolyte
makes up from 0.01 wt. % to about 20 wt. % of the composition.
5. The composition of claim 1, wherein the persulfate donor makes
up from about 70 wt. % to about 99.98 wt. % of the composition.
6. The composition of claim 1, wherein the transition metal
catalyst and cationic electrolyte coat the persulfate donor.
7. The composition of claim 1, wherein the composition is dissolved
in water to form a solution that is delivered to the water.
8. The composition of claim 1, wherein the composition is
powder.
9. The composition of claim 1, wherein the composition is
granular.
10. The composition of claim 1, wherein the composition is an
agglomerate.
11. The composition of claim 10, wherein the agglomerate comprises
an outer layer and an inner layer, the outer layer containing the
persulfate donor and the transition metal catalyst and the inner
layer containing the cationic electrolyte.
12. The composition of claim 10, wherein the agglomerate comprises
the cationic electrolyte encapsulated by a mixture of persulfate
donor and catalyst.
13. The composition of claim 10 further comprising an agent that
restricts a dissolution rate of the agglomerate in water.
14. The composition of claim 13, wherein the agent is a
substantially water-insoluble wax.
15. The composition of claim 13, wherein the agent is a mineral
salt of a carboxylic acid having at least 16 carbons.
16. The composition of claim 13, wherein the agent is a gel forming
material that forms a gelatinous structure upon contacting
water.
17. The composition of claim 1, wherein the persulfate donor is at
least one of: potassium monopersulfate, sodium persulfate, and
potassium persulfate.
18. The composition of claim 1, wherein the transition metal
catalyst is a silver ion donor.
19. The composition of claim 1, wherein the transition metal
catalyst is a copper ion donor.
20. The composition of claim 1, wherein the transition metal
catalyst comprises cobalt.
21. The composition of claim 1, wherein the transition metal
catalyst comprises iron.
22. The composition of claim 1, wherein the transition metal
catalyst comprises molybdenum.
23. The composition of claim 1, wherein the transition metal
catalyst comprises platinum.
24. The composition of claim 1, wherein the transition metal
catalyst comprises manganese.
25. The composition of claim 1 further comprising a chelating agent
in contact with the transition metal catalyst.
26. The composition of claim 1, wherein the composition is usable
while mammals are present in the water.
27. The composition of claim 1, wherein the cationic electrolyte is
an inorganic salt.
28. The composition of claim 27, wherein the inorganic salt is
alum.
29. The composition of claim 27, wherein the inorganic salt is an
aluminate.
30. The composition of claim 1, wherein the cationic electrolyte is
an organic polymer.
31. The composition of claim 30, wherein the organic polymer is a
polyacrylamide.
32. The composition of claim 30, wherein the organic polymer is
chitosan.
33. A composition for reduction of chemical oxygen demand in water,
the composition comprising: a free halogen donor; a persulfate
donor; a cationic electrolyte; and a transition metal catalyst,
wherein the free halogen donor, the persulfate donor, the cationic
electrolyte and the transition metal catalyst form an
agglomerate.
34. The composition of claim 33, wherein the composition is soluble
in water.
35. The composition of claim 33, wherein the persulfate donor is at
least one of: potassium monopersulfate, sodium persulfate, and
potassium persulfate.
36. The composition of claim 33, wherein the catalyst is present in
an amount between about 0.00001 wt. % and 10 wt. % of the
composition.
37. The composition of claim 33, wherein the transition metal
catalyst is a silver ion donor.
38. The composition of claim 33, wherein the transition metal
catalyst is a copper ion donor.
39. The composition of claim 33, wherein the transition metal
catalyst comprises cobalt.
40. The composition of claim 33, wherein the transition metal
catalyst comprises iron.
41. The composition of claim 33, wherein the transition metal
catalyst comprises molybdenum.
42. The composition of claim 33, wherein the transition metal
catalyst comprises platinum.
43. The composition of claim 33, wherein the transition metal
catalyst comprises manganese.
44. The composition of claim 33 further comprising a chelating
agent in contact with the transition metal catalyst.
45. The composition of claim 1, wherein the cationic electrolyte is
an inorganic salt.
46. The composition of claim 45, wherein the inorganic salt is
alum.
47. The composition of claim 45, wherein the inorganic salt is an
aluminate.
48. The composition of claim 33, wherein the cationic electrolyte
is an organic polymer.
49. The composition of claim 48, wherein the organic polymer is a
polyacrylamide.
50. The composition of claim 48, wherein the organic polymer is
chitosan.
51. The composition of claim 33, wherein the free halogen donor is
at least one of: calcium hypochlorite, trichloroisocyanuric acid,
dichloroisocyanuric acid, dibromodimethyl hydantoin,
bromochlorodimethyl hydantoin, and lithium hypochlorite.
52. The composition of claim 33, wherein the persulfate donor is
separated from the free halogen donor.
53. The composition of claim 33 further comprising a chlorite
donor.
54. The composition of claim 33, wherein the free halogen donor
comprises about 50-99 wt. % of the composition.
55. The composition of claim 33, wherein the persulfate donor and
the transition metal catalyst comprise about 1-50 wt. % of the
composition.
56. The composition of claim 33 further comprising an agent that
restricts a dissolution rate of the composition.
57. The composition of claim 56, wherein the agent is a
substantially water-insoluble wax.
58. The composition of claim 56, wherein the agent is a mineral
salt of a carboxylic acid having at least 16 carbons.
59. The composition of claim 56, wherein the agent is a gel forming
material that forms a gelatinous structure upon contacting
water.
60. The composition of claim 33, wherein the composition is usable
while mammals are present in the water.
61. The composition of claim 33, wherein the agglomerate consist
includes an inner layer and an outer layer, the outer layer
containing the free halogen donor, the persulfate donor, and the
transition metal catalyst, and the inner layer containing the
cationic electrolyte.
62. The composition of claim 33, wherein the agglomerate comprises
the cationic electrolyte encapsulated by a mixture of free halogen
donor, persulfate donor, and catalyst.
63. A method of removing chemical oxygen demand from water, the
method comprising: preparing a persulfate solution by contacting
the persulfate to water; adding a catalyst to the persulfate
solution; adding a cationic electrolyte to the persulfate solution;
and feeding the persulfate solution to the water.
64. The method of claim 63, wherein the persulfate, the catalyst,
and the cationic electrolyte are admixed prior to forming the
persulfate solution.
65. The method of claim 63 further comprising: agglomerating the
persulfate, the catalyst, and the electrolyte to form an
agglomerate; and placing the agglomerate in a dispenser such that
the agglomerate contacts water and forms a
persulfate-catalyst-cationic electrolyte solution.
66. The method of claim 65, wherein agglomerating the persulfate,
catalyst, and electrolyte comprises forming an agglomerate of
multiple layers.
67. The method of claim 66, wherein forming the agglomerate of
multiple layers comprises: forming an outer layer containing the
persulfate and the catalyst; and forming an inner layer containing
the cationic electrolyte.
68. The method of claim 67, wherein the agglomerate in the
dispenser releases a persulfate-catalyst solution upon dissolving
the outer layer before releasing the cationic electrolyte into the
water.
69. The method of claim 63, wherein the catalyst is a silver ion
donor.
70. The method of claim 63, wherein the catalyst is a copper ion
donor.
71. The method of claim 63, wherein the catalyst comprises
cobalt.
72. The method of claim 63, wherein the catalyst comprises
iron.
73. The method of claim 63, wherein the catalyst comprises
molybdenum.
74. The method of claim 63, wherein the catalyst comprises
platinum.
75. The method of claim 63, wherein the transition metal catalyst
comprises manganese.
76. The method of claim 63 further comprising adding a chelating
agent to the composition.
77. The method of claim 63, wherein the persulfate donor is at
least one of: potassium monopersulfate, sodium persulfate, and
potassium persulfate.
78. The method of claim 63, wherein the cationic electrolyte is an
inorganic salt.
79. The method of claim 78, wherein the inorganic salt is alum.
80. The method of claim 78, wherein the inorganic salt is an
aluminate.
81. The method of claim 63, wherein the cationic electrolyte is an
organic polymer.
82. The method of claim 81, wherein the organic polymer is a
polyacrylamide.
83. The method of claim 81, wherein the organic polymer is
chitosan.
84. The method of claim 63, wherein the adding and the feeding are
done while mammals are present in the water.
85. A composition for removing chemical oxygen demand from an
aquatic facility, the composition comprising: a transition metal
catalyst in an amount that makes up between about 0.01 wt. % and
about 10 wt. % of the composition; a cationic electrolyte in an
amount that makes up between about 0.01 wt. % to about 20 wt. % of
the composition; and a persulfate donor in an amount that makes up
between about 70-99.98 wt. % of the composition.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This patent application is a continuation-in-part (CIP) of
U.S. patent application Ser. No. 11/158,676 filed on Jun. 22, 2005,
the content of which is incorporated by reference herein in its
entirety.
FIELD OF INVENTION
[0002] This invention relates generally to cleaning an aquatic
facility and more particularly to cleaning an aquatic facility that
contains organic contaminants.
BACKGROUND
[0003] Aquatic facilities such as swimming pools and spas have
become increasingly popular in private homes, hotels, fitness
centers, and resorts. To ensure that the aquatic facilities can be
enjoyed safely, the water must be treated to reduce or eliminate
chemical oxygen demands (COD) and/or total organic carbon (TOC).
When the COD and/or TOC increases in the water, the oxidation
reduction potential of the water decreases and oxidizers are added
to maintain a healthy level of oxidation reduction potential. A
common oxidizer that is used in aquatic facilities is chlorine or
bromine. However, when chlorine or bromine is present in the water
above a certain level in the presence of COD and/or TOC,
trihalomethanes (THM) and chloramines form in the water
undesirably.
[0004] Common ingredients for treating water systems include
various persulfate salts and persulfate donors such as potassium
monopersulfate (PMPS), which is typically available in the form of
a triple salt,
(KHSO.sub.5).sub.x.(KHSO.sub.4).sub.y.(K.sub.2SO.sub.4).sub.z
(herein referred to as "PMPS triple salt"). However, persulfate
salts, such as potassium persulfate (K.sub.2S.sub.2O.sub.8), are
difficult to use because they cause severe irritation to facility
users (e.g., swimmers, bathers) at concentrations above about 2
ppm. The strong oxidation potential of PMPS triple salt makes it
effective for decreasing the concentration of COD. Typically, these
chemicals are applied to the aquatic facility through a "shock
treatment" whereby the facility is evacuated and the product is
broadcast across the water surface. The facility users may not be
allowed to come in contact with the treated water for a period of
time after the treatment due to concerns for irritation.
[0005] PMPS usually contains potassium persulfate
(K.sub.2S.sub.2O.sub.8) as a result of being prepared using oleum.
Persulfates have a long halflife in aquatic water facilities and
are undesirable. As a result of the concerns for irritation
resulting from accumulation of persulfate, PMPS can be used only at
limited dosages, which typically do not exceed two pounds per
10,000 gallons of water per week.
[0006] While PMPS maintains the water quality in aquatic facilities
reasonably well, it is not convenient to use because of the need to
evacuate the facility during use and the fact that it can only be
used in limited doses regardless of how heavily the facility is
used. Thus, a way of cleaning the water without these inconvenient
limitations is desired.
SUMMARY
[0007] In one aspect, the invention is a composition for reducing
chemical oxygen demand in water. The composition includes a
persulfate donor, a transition metal catalyst in contact with the
persulfate donor, and a cationic charged electrolyte. The cationic
electrolyte coagulates the spent transition metal catalyst,
facilitating the removal of the catalyst from the water.
[0008] In another aspect, the composition includes a free halogen
donor, a persulfate donor, a cationic electrolyte, and a transition
metal catalyst. The free halogen donor, the persulfate donor, the
cationic electrolyte, and the transition metal catalyst form an
agglomerate.
[0009] In yet another aspect, the invention is a method of removing
chemical oxygen demand from water. The method entails preparing a
persulfate solution, adding a catalyst to the persulfate solution,
adding a cationic electrolyte to the persulfate solution, and
feeding the persulfate solution to the water.
[0010] The invention is also a composition for removing chemical
oxygen demand from an aquatic facility, wherein the composition
includes: a transition metal catalyst in an amount that makes up
between about 0.01 wt. % and about 10 wt. % of the composition, a
cationic charged electrolyte that makes up between about 0.05 wt. %
and about 20 wt. % of the composition, and a persulfate donor in an
amount that makes up between about 70-99.98 wt. % of the
composition.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 shows an agglomerate having multiple layers.
[0012] FIG. 2 shows an alternative embodiment of the agglomerate
having multiple layers.
DETAILED DESCRIPTION OF THE EMBODIMENT(S)
[0013] As used herein, a "persulfate donor" is any compound or
composition that includes at least 0.5 wt. % S.sub.2O.sub.8.sup.2-
donor, such as sodium persulfate, potassium persulfate, and PMPS
(potassium monopersulfate) produced from oleum.
[0014] The invention discloses a composition and a method for
removing the COD from aquatic facilities while the facility is
being used by swimmers, bathers, etc. With the invention, the COD
is decomposed as it is added to the water. Thus, the formation of
THMs and chloramines is significantly reduced and the quality of
air and water around the aquatic facilities is enhanced.
[0015] The invention allows the application of potentially
irritating oxidants (e.g., potassium persulfate) while the water is
being used by swimmers/bathers. Irritation to the bathers is
avoided by using a catalyst that rapidly reacts with the persulfate
to form sulfate free radicals. This rapid catalyzed reaction
eliminates the concern of persulfate accumulation, and effectively
decomposes the organic contaminants shortly after being added to
the water, thereby preventing their accumulation.
[0016] The invention entails applying a catalyst to the water to
maintain an "effective catalyst concentration," which is between
about 1 ppb and about 1 ppm, more preferably between about 5 ppb
and about 500 ppb. A persulfate donor is added to the water,
inducing the in-situ generation of sulfate free radicals through a
catalyzed reaction. Sulfate free radicals have a reported potential
of about 2.6 v. The cationic electrolyte, the catalyst, and the
persulfate donor may be added separately to the water. Preferably,
the catalyst and the persulfate are added at or around the same
time as each other since the catalyst is required to induce the
formation of the free radicals. The cationic electrolyte may be
added to the water after the catalyst is spent to remove the spent
catalyst.
[0017] When a low level of persulfate is applied to water in the
presence of the catalyst, sulfate free radicals are formed that
effectively decompose the organic compounds, as follows:
S.sub.2O.sub.8.sup.2-+Catalyst.fwdarw.Catalyst+SO.sub.4.sup.2-+.SO.sub.4.-
sup.- .SO.sub.4.sup.2-+H.sub.2O.fwdarw.OH.sup.-.+HSO.sub.4.sup.-
When the sulfate free radicals decompose the organic compounds, any
sanitizer (e.g., free halogen donor) in the water is freed to
effectively control the bacteria and viral counts.
[0018] The persulfate donor may be potassium monopersulfate, sodium
persulfate, potassium persulfate, or any combination thereof.
[0019] The catalyst may be a transition metal donor, e.g. silver or
copper ion donor. In some embodiments, the catalyst may also be
cobalt, iron, molybdenum, platinum, manganese, or a combination
thereof. If desired, a chelating agent may be included to delay and
extend the performance of the catalyst. To limit or prevent the
catalyst from precipitating, the pH of the water is preferably
maintained at between about 6.8 and about 8.0, and more preferably
between about 7.0 and about 7.8. The transition metal catalyst may
make up between about 0.01 wt. % and about 10 wt. % of the
composition.
[0020] The cationic electrolyte may be an inorganic salt such as
Alum or sodium aluminate, or an organic polymer such as
polyacrylamide or chitosan. The cationic electrolyte coagulates the
spent catalyst.
[0021] In one exemplary embodiment, the transition metal catalyst
constituted between about 0.01 wt. % and about 10 wt. % of the
composition, the persulfate donor constituted between about 70 wt.
% and about 99.98 wt. % of the composition, and a cationic charged
electrolyte made up about 0.05-20 wt % of the composition.
[0022] The persulfate donor, the cationic electrolyte, and the
catalyst can also be combined with a free halogen donor. Free
halogen donors act as effective sanitizer/oxidizer that rids the
water of inorganic nitrogen such as mono- and di-chloroamines.
Where free halogen donor is incorporated into the composition, the
free halogen donor may make up between about 50-99 wt. % of the
composition. The persulfate donor, the cationic electrolyte, and
the catalyst would make up about 1-50 wt. % of the composition. The
catalyst alone may make up about 0.00001 wt. % to 10 wt. % of the
composition, and the cationic charged electrolyte would make up
about 0.05-20 wt. % of the composition.
[0023] The composition can be either a powder mixture, granular
mixture, or agglomerate containing the persulfate donor, cationic
electrolyte, and the catalyst. The composition of the invention
effectively delivers the persulfate donor to the water while
maintaining the effective catalyst concentration in the water.
[0024] To form the powder mixture, the catalyst and the cationic
electrolyte are admixed with the persulfate donor in a mixer such
as a ribbon mixer or equivalent mixing or tumbling equipment.
[0025] To form the granules, the persulfate donor may be prepared
into granules and coated with the catalyst and cationic
electrolyte. The catalyst and the cationic electrolyte may be
deposited on the surface of the granule uniformly or nonuniformly.
In some embodiments, the coating may include a barrier film that
isolates the persulfate donor from the surrounding environment
(e.g., a free halogen donor).
[0026] The persulfate-catalyst-electrolyte powder mixture or the
persulfate granules coated with the catalyst and the cationic
electrolyte can be used as is or agglomerated under pressure to
form a tablet. The agglomerate/tablet is made of a plurality of
granules or powder packed into a tablet of the desired shape. The
agglomerate may contain an agent that restricts the dissolution
rate of the tablet. Examples of such agents include a substantially
water-insoluble wax such as polyethylene wax, polyoxyethylene wax
and their respective fatty acid ester wax. An agent can also be a
mineral salt of a carboxylic acid having at least 16 carbons, such
as calcium stearate and similar hydrocarbon-based salts. Further
still, the agent may be a gel-forming material such as a
polaxamers, polyacrylic acid, polyacrylamide, polyvinyl alcohol,
polysaccharides such as Xanthan, and various cellulose-based
derivatives. The gel-forming material forms a gelatinous structure
upon being exposed to water, effectively controlling the rate at
which the agglomerate dissolves in the water.
[0027] FIG. 1 shows an agglomerate (also referred to as a "tablet")
having multiple layers. An outer layer 101 contains the persulfate
donor, the catalyst, and halogen if applicable. An inner layer 100
contains the cationic electrolyte. The outer layer 101 surrounds or
encapsulates the inner layer 100 so that when the agglomerate comes
in contact with water, the persulfate donor and the catalyst will
be released before the cationic electrolyte is released. This order
of release is advantageous because the persulfate donor and the
catalyst induce formation of sulfate free radicals that enhance the
destruction of the COD. Then, the cationic electrolyte precipitates
the spent catalyst to prevent the spent catalyst from accumulating
in the water. The multi-layered agglomerate is formed by putting a
small amount of core component (i.e., the cationic electrolyte)
between the surrounding components (i.e., the catalyst, the
persulfate donor, and the halogen admixed together) before being
pressed. Alternatively, a smaller tablet of the core component may
be formed first, then surrounded by the powder of the surrounding
components, and pressed.
[0028] FIG. 2 shows an alternative embodiment of the agglomerate
having multiple layers. In this embodiment, a layer 200 containing
the cationic electrolyte is sandwiched between layers 201 that
contains the persulfate donor, the catalyst, and the halogen if
applicable. To produce the embodiment of FIG. 2, the persulfate
donor and the catalyst are admixed and pressed to form a layer. A
separate layer of cationic electrolyte is formed, also by pressing,
and the two types of layers are combined.
[0029] The embodiment of FIG. 1 encases the coagulant so that most
or all of the persulfate donor and catalyst are released before the
coagulant (cationic electrolyte) is released, ensuring that
reactions take place before the catalyst is removed. The embodiment
of FIG. 2 may be used where the catalyst is chelated. In the
embodiment of FIG. 2, some coagulant will be released at the same
time as the persulfate donor and the catalyst. However, if the
catalyst is chelated, the chelant prevents the catalyst from coming
in contact with the coagulant until the catalyst is spent and the
chelant is destroyed.
[0030] The agglomerate can be commercially produced using a
multi-layer tableting equipment such as a "Hata three-layer
tableting press" sold by Elizabeth-Hata International, located at
14559 Route 30, 101 Peterson Drive, North Huntingdon, Pa. However,
a Carver press can also be used for laboratory scale productions
using established tableting techniques.
[0031] The composition can also be combined with a sanitizer such
as trichloroisocyanuric acid. Chemical oxygen demand generally
impedes the sanitizer from performing its function. When the
composition removes the chemical oxygen demand, the sanitizer is
able to effectively improve the water quality without
impediment.
[0032] The composition may be used periodically to prevent the COD
level in water from getting too high. It may also be used to
recover aquatic facilities that are already highly contaminated
with organic based COD.
EXAMPLE 1
[0033] 1000 mL of a water-based stock solution containing 7.0 ppm
persulfate was prepared by adding potassium persulfate (purchased
from Sigma-Aldrich) to water and adjusting the pH to 7.2 using
sodium bisulfate. The persulfate level was initially and
periodically tested using ammonium thiocyanate and ferrous iron in
an acidic solution. The stock solution was divided into 2-500 mL
samples, and magnetic stirring rods were added to each sample.
Using the magnetic stirrer, each sample was vigorously mixed to
achieve a vortex reaching approximately half the distance to the
stirring rod. TABLE-US-00001 TABLE 1 Persulfate Decomposition Rate
Lapsed Time Persulfate Conc. (ppm) Persulfate Conc. (ppm) (Hrs.)
with 0.63 ppm Ag catalyst with 0.31 ppm Ag catalyst 0 7.0 7.0 3 4.2
5.6 5 2.1 4.2 7 <1.0 2.8
[0034] Table 1 shows that the persulfate concentration decreased
with time. The test results in Table 1 illustrate that the
catalyst, under conditions like those experienced in pools, can
effectively decompose the persulfate irritant.
[0035] As the reactions proceed and the hydroxyl radicals are
reduced, the pH of the solution increases. Therefore, during the
test period, the pH was measured every 30 minutes and a solution of
sodium bisulfate was administered as needed to maintain the pH at a
range of about 7.2 to 7.5.
[0036] The test result indicates that when the reaction occurs in
COD-laden water, the sulfate free radicals will enhance the
effectiveness of the treatment (e.g., PMPS treatment) for
decomposing the COD. Moreover, with the persulfate irritant being
removed rapidly with the catalyst, the invention allows PMPS (which
is usually accompanied by some persulfate) to be applied while
swimmers and bathers are present in the water.
EXAMPLE 2
[0037] 0.6 grams of potassium persulfate (K.sub.2S.sub.2O.sub.8)
was dissolved in 99.4 grams of water. Sodium bisulfate was added to
drop the pH to 3.4. A sample of this potassium-persulfate-solution
was taken and diluted with water to achieve a water to sample
weight ratio of 99:1. The persulfate concentration was measured at
49 ppm.
[0038] 0.1 grams of cuprous chloride (CuCl) was added to the stock
persulfate solution and mixed for 10 minutes. Then, a sample of
this CuCl-persulfate-solution was taken and diluted to a
water-sample weight ratio of 99:1. The persulfate concentration in
the resulting solution was 0.0 ppm.
[0039] Another sample of the CuCl-persulfate-solution was taken and
diluted with 99:1 weight ratio of water to sample to prepare a
stock solution. The resulting copper (Cu) concentration was 4.9
ppm.
[0040] 0.1 grams of alum was added to the stock solution, the pH
was raised to 7.3, and the sample was mixed for 5 minutes. The
sample was then allowed to settle. A sample was decanted, diluted,
and tested for copper. The resulting copper (Cu) concentration was
0.78 ppm.
[0041] The tests in the Examples above show that the catalyst,
under the low pH conditions, effectively remove the persulfate by
converting the persulfate to sulfate free radicals in the presence
of a cationic electrolyte (alum) at near neutral pH conditions. The
spent catalyst was effectively coagulated and removed from the
solution.
[0042] The composition, which is substantially soluble in water,
may be made into a solution before being added to the COD-laden
water. In some cases, the solution is prepared in a container
before being delivered to the pool by an eductor system, a chemical
metering pump, or pressure differential between the inlet and
outlet water supply of the container. In other cases, the solution
is made by adding the composition (e.g., in agglomerated form) to
the circulating water of the system.
[0043] If desired, additional persulfate donor can be fed
separately to the water to further enhance the formation of sulfate
free radicals.
[0044] Although preferred embodiments of the present invention have
been described in detail hereinabove, it should be clearly
understood that many variations and/or modifications of the basic
inventive concepts herein taught which may appear to those skilled
in the present art will still fall within the spirit and scope of
the present invention.
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